The author seems to miss that relational algebra was developed for the needs of the databases of the time, i.e. in an effort to optimize reads off spinning iron. Any effort for async is destroyed by blocking fs syscalls.
It starts with "Future users of large data banks must be protected from having to know how the data is organized in the machine (the internal representation)".
It goes on to say, "(The relational model) provides a means of describing data with its natural structure only - that is, without superimposing any additional structure for machine representation purposes".
For some more backstory[1] see Sowa, who was also an IBM researcher at the time:
George Boole (1847, 1854) applied his algebra to propositions, sets, and monadic predicates. The expression p×q, for example, could represent the conjunction of two propositions, the intersection of two sets, or the conjunction of two monadic predicates. With his algebra of dyadic relations, Peirce (1870) made the first major breakthrough in extending symbolic logic to predicates with two arguments (or subjects, as he called them). With that notation, he could represent expressions such as "lovers of women with bright green complexions". That version of the relational algebra was developed further by Ted Codd (1970, 1971), who earned his PhD under Arthur Burks, the editor of volumes 7 and 8 of Peirce’s Collected Papers. At IBM, Codd promoted relational algebra as the foundation for database systems, a version of which was adopted for the query language SQL, which is used in all relational database systems today. Like Peirce’s version, Codd’s relational algebra and the SQL language leave the existential quantifier implicit and require a double negation to express universal quantification.
This doesn't seem consistent with the history of relational algebra. It was introduced at a time when there were numerous competing storage technologies from cartridges, strips, drums, as well as disk drives all of which had different physical characteristics.
In fact disk drives were the least common storage system, they were the fastest but most expensive and had the least storage.
The Wikipedia entry on relational algebra does not even mention disks. Given this (together with what I recall from Codd's seminal papers on the concept), I am not inclined to believe it has anything to do with disks specifically, just on your say-so. If you have something more to say in support of your position, I will give it all due consideration.
